Ultrasound elastography for thyroid nodules: a reliable study?

The aims were to determine the reliability of ultrasound elastography (USE) and the factors related to reliability. One hundred six solid thyroid nodules in 78 consecutive patients were enrolled. Conventional ultrasound examination and USE were performed for each nodule. We evaluated reliability, the factors affecting reliability of USE and the interobserver and intraobserver agreement. We suggest following three criteria as less reliable results: (1) <50% green color in the region of interest box for the thyroid parenchyma; (2) discordance in elasticity scores in the three USE images; and (3) intranodular color signal loss. Consensual reliability of USE was 68% (72/106). Multivariable logistic regression analysis revealed that rim calcification (p = 0.002), a compressive force of ≥3 (p < 0.001) and arterial pulsation (p < 0.001) were significantly associated with reliability of USE. Substantial interobserver (κ = 0.738) and intraobserver agreement were observed in reliable USE results (κ = 0.765). Clinical application of USE should be restricted to the thyroid nodules with reliable results.